1,2-Bisanionic coupling approach to 2,3-disubstituted cyclopentenols and cyclopentenones.
Marco Luparia, Alessandro Vadalà, Giuseppe Zanoni, Giovanni Vidari
Index: Org. Lett. 8 , 2147, (2006)
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Abstract
[reaction: see text] We describe a new approach to 2,3-disubstituted cyclopentenols and cyclopentenones through two consecutive regioselective additions of equal or different electrophiles to a cyclopentene bisanionic synthon. Indeed, on exposure to BuLi, 3-bromo-2-iodocyclopent-2-enol O-TBS ether undergoes iodine-lithium permutation with complete regioselectivity. Successive reaction of the monolithium anion with different C(sp(2))- and C(sp(3))-electrophiles affords the corresponding 2-substituted-3-bromocyclopentenol derivative. Subsequent bromo-lithium exchange with t-BuLi, followed by reaction with an equal or different electrophile, affords the desired 2,3-disubstituted cyclopentenol.